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169

We do. Normally the reflections are too quick to hear distinctly, and in an environment like a room they rapidly become diffused into a mush which a sound engineer would call reverberation. In larger spaces you can often hear distinct echoes as well or instead: a good way to play with this is to clap your hands (once) in a quiet hall: you will hear the ...


47

Our eyes have excellent spatial resolution. We can tell the difference between objects only a fraction of a degree apart. This is possible due to both the construction of the eye and the fact that visible light has wavelengths that are tiny on our scale. Signals that arrive simultaneously can be independently detected. Our ears do not have this level of ...


24

As someone who's done substantial amounts of live sound for bands, often in rooms in pubs which are acoustically "interesting", it certainly does happen with sound, and you and everyone else hear it all the time. My only possible conclusion is that you haven't listened carefully enough to what you hear. The reason people like singing in the bathroom is ...


17

The main reason why we don't hear reflections of sound is related to how our hearing works. The psychoacoustic explanation to this is called the precedence effect. It states that when two or more sounds arrive to the listener within a short enough time(roughly under 50ms) this is perceived as a single sound event. The localization of the sound is dominated ...


15

Your question seems to imply that you think that, over a deep-ocean tsunami where the wave is travelling at speeds in excess of the speed of sound in air, the water in the wave is travelling faster than that speed of sound. This is not the case. The wave is travelling faster than the speed of sound in air, but the wavelength of the wave is so long that the ...


14

As the above answers have stated, we do hear such reflected sound but normally do not notice. However, if you ever get the opportunity stand inside a closed anechoic chamber. You will then "hear" the total absence of all reflected sound. To say it is weird is an understatement - it feels like your ears are being sucked out by silence.


11

Whispering rooms/galleries are another good example. In the simplest case, an elliptical room, sound echoing off the walls allows one person standing at one focus of the ellipse to clearly hear everything at the other focus. Step away from the focus, though, and the effect disappears.


8

Some blind people actually use sonar-like techniques to "see". This is in the press from time to time, e.g. http://www.sciencemag.org/news/2014/11/how-blind-people-use-batlike-sonar.


4

Some good answers here but one area that has not been covered is a sort of threshold effect. An ear senses sound pressure, not "rays" of sound. So it responds mainly to the strongest signals, and the brain tends to tune out noise. We attend to one signal in sound, generally speaking. But for vision, all that "noise" of light bouncing around off of objects IS ...


3

It's probably the temperature of glass itself. Speed of sound in solids depends on the elastic moduli (the choice of the modulus depends on the polarization of sound - in this case, it's mostly transverse motion, as you are observing glass oscillation). The change of the density of the hot air may also contribute. Possible contributions and why they can be ...


3

In short, yes, it will be louder. In the simplest case, if you were able to duplicate the exact signal everywhere in space, you would actually get 4 times the intensity - sound waves add linearly, but intensity adds quadratically. For two uncorrelated sources (if you played different white noise signals through each speaker) you would only get a factor ...


3

This is a common misconception about what boundary conditions do and how they do it (for example here). You discussed two types of boundary conditions, Neumann and Dirichlet. In Neumann boundary conditions, we impose that the derivative of the variable normal to the boundary is specified, generally to be zero. With Dirichlet, we impose the value that the ...


3

This is related to so called room modes. These are caused by standing waves forming between two walls or between the floor and ceiling. With a room that you described the frequencies where these waves form should be somewhere around 50-100Hz. What this means in practice is that when standing in a position where such a wave forms, there is a strong boost to ...


2

Take your expression: $$ v=\frac{\omega}{k} \tag{1} $$ We'll write $\omega=2\pi f$, rather than $\omega = 2\pi/\tau$, where $f$ is the frequency of the wave and substitute for $\omega$ and $k$ in equation (1) to get: $$ v = f\lambda \tag{2} $$ The wavelength $\lambda$ is the distance the wave moves in one cycle, and the frequency is the number of cycles ...


2

I don't fully comprehend why the positive (and therefore quicker) parts appear to be retarding and eventually making a N-like sawtooth wave? I wrote a more detailed answer at http://physics.stackexchange.com/a/139436/59023, but the basic idea is that the larger amplitude parts of the wave have a higher phase velocity than the lower amplitude parts. ...


2

Why don't we hear sound reflecting that much? Mainly, it has to do with energy and wavelength. When light hits an object with rough surfaces such as a building, it is scattered in every direction. Because the light illuminating the building has such a high energy, your eye is able to pick up on just a tiny fraction of that scattered light, in spite of ...


2

This is purely a matter of human perception. Our eyes contain literally millions of separate photoreceptors, which enables us to build up a clear picture of our surroundings. On the other hand we have only two ears! Admittedly each ear is able to differentiate a wide range of frequencies, and in that way has a superiority over the eye, which can only ...


2

It is because of our reaction time ,speed of sound and disturbance in atmosphere. As our reaction time is 1/10th of a second and speed of sound is about 343.2 metres per second. So sound travels 34.32 metres in 1/10th of a second. To distinguish between 2 sounds the distance between them must be 34.32 metres and if we want to notice reflection of sound(echo) ...


1

I know nothing about the engineering aspect, but you get a doppler shift for a radio signal whatever the angle that the plane's velocity is to the line of sight. If you are at the centre of a circular motion, then the shift can be attributable to the time dilation experienced by the plane and the observed frequency is decreased by a factor ...


1

Glass contracts when heated. This means the individual molecules compact as they meet the heat catalyst. This is one reason for the resonance difference. But also: If you take two separate glasses and fill them at different levels of room temperature water you will find they have different resonant frequencies as well. So in your heated liquid experiment ...


1

A compression shock at subsonic flight speed only occurs when a supersonic pocket of air collapses downstream. Neither of your options is correct, and in that shock the speed drops from mildly supersonic (typically Mach 1.25) to the inverse of that Mach number (that would then be typically Mach 0.8). Acceleration into the supersonic regime is smooth and ...


1

There is an addition needed here. The speed of a wave is constant through a homogeneous isotropic medium. Sound wave is a mechanical wave which propagates as compression and rarefaction through the medium. It actually pressurizes and depressurizes certain region of medium. The medium has several properties upon which the velocity of sound relies up on. If ...


1

This demonstration using the Ruben's tube set-up might help. I always found this to be one of the most exciting visual demonstrations of sound waves.


1

Remember that noise is unwanted frequency signal superimposed into the original frequency. This means to reduce noise, you need to block the unnecessary frequency components. The effect of noise increases while increasing the amplitude because amplitude is a measure of loudness. So the amplitude (loudness) of the noise also increase as you increase the ...



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